As always, you can check the Windows Lifecycle Fact Sheet to confirm.
If you happen to have a machine that either "got stuck" on version 1607 or did something to stop updates, all security updates for this version will cease. It's time to update to Version 1803, following the instructions for Updating Windows 10 using the Windows 10 ISO file, using the ISO file you download using the Media Creation Tool from the Microsoft Windows 10 Download Page.
You should wait until the Microsoft Windows 10 Download Page shows the Spring Creators Update as having been released. Right now it still shows Fall Creators Update, and it could be a few hours to a few days before it is changed for the Spring Creators Update.